Immunodominant human T-cell epitopes of Hepatitis C virus

Abstract: The present invention relates to a polypeptide of about 8 to about 100 amino acids comprising or consisting of at least 8 contiguous amino acids selected from the E1 region of the HCV polyprotein, with said contiguous amino acids containing a T-cell stimulating epitope.

Description: The present invention describes immunodominant hepatitis C virus T cell epitopes useful in hepatitis C prophylactic and therapeutic vaccines, derived from the HCV, E1, protein. Technical field of the invention The present invention relates to the production of novel synthetic immunogens related to the hepatitis C virus E1, region and to the use thereof in the production of vaccines, therapeutic agents and the like. More specifically, the present invention relates to polypeptide compositions containing E1, T cell determinants. Background of the invention In the few years since its discovery, Hepatitis C virus (HCV) has been shown to be a major cause of acute and chronic liver disease. HCV is a single-stranded RNA virus with a genome of approximately 9400 nucleotides that consists of a 5' untranslated region (5'UR) of 341 nucleotides which precedes a single large open reading frame encoding a precursor polyprotein of about 3010 amino acids (Kato et al., 1990). The genetic organization of the viral genome is related to that of flavi-and pestiviruses, with the putative structural proteins located in the N-terminal region and a variety of non structural proteins located at the C-terminal end of the polyprotein. The structural proteins are the core protein (C, amino acids 1-191) followed by the putative envelope proteins E1 (amino acids 192-383) and E2/NS1 (amino acids 384-746). The terms E2 and NS1 are often used interchangeably. Another form of E2 is composed of amino acids 384 to 809 and a third form is associated with NS2. The non structural proteins are NS2, NS3, NS4 and NS5, of which at least NS4 and NS5 have been shown to be further processed into NS4A, NS4B, NS5A, and NS5B. Structural analysis of HCV genomes revealed the existence of different genotypes that have been classified into types and subtypes (Stuyver et al., 1993). The sequence diversities are distributed along the whole genome including the 5' untranslated region. The highest sequence variability has been observed in the NS2 and 3' untranslated regions, and in the putative envelope regions encoding the E1 and E2 proteins. The core, NS3, and certain regions of the NS4 proteins displayed markedly less diversity (Okamoto et al., 1992). HCV humoral response Soon after the discovery of HCV, immunoassays for the detection of circulating antibodies against HCV proteins became widely available. These tools have led to an explosive increase of the knowledge in the field of the human humoral immune response to HCV in different conditions. Once it was demonstrated that HCV was the major cause of posttransfusional non-A, non-B hepatitis, the search for antibodies to HCV was added to the safety screening panel of blood products. This procedure not only increased the safety of blood transfusions but also enhanced the knowledge of the epidemiology of the virus. The fact that HCV is responsible for a large proportion of chronic hepatic infections in which blood transfusion or parenteral inoculation are excluded remains a major challenge for further epidemiological studies. The widespread use of the assays for the detection of antibodies to HCV has also led to the recognition of the regions with humoral antigenicity of the virus. The relationship between the kinetics and magnitude of the humoral immune response to the different proteins of HCV and the course and outcome of the disease remains to be established. HCV T cell epitopes The immune response to viral antigens is almost entirely T cell dependent. T cells are required both for antibody production and for some cytotoxic reactions. HCV-encoded proteins are immunogenic not only at the B cell level, but also at the T cell level. Studies describing the cellular immune response to HCV are scarce. Lin et al. (1993) describe candidate T cell epitopes within absolutely conserved regions of HCV gene obtained by means of a computer search revealing a large number of potential T cell epitopes. It has also been reported that peripheral blood cell monocytes (PBMC) from HCV-infected individuals proliferate in response to HCV recombinant proteins and that peripheral responses to core protein correlate with a benign course of infection (Botarelli et al., 1993). In the liver of patients with chronic HCV infection HCV-specific, HLA class I- restricted cytotoxic T lymphocytes (CTL) have been identified and cloned that recognize epitopes in E1 and NS2 proteins. These investigators have mainly focused on obtaining T cell clones from individual patients, and on the localization of the immunoreactive domain for the single CTL clones. Such studies led to the discovery of the epitope ASRCWVAM (aa 235-242) in the aminoterminal part of the E1 protein, and of the epitope LMALTLSPYYKRY (aa 826-838) from the NS2 region (Koziel et al., 1992). In patients with chronic HCV hepatitis intrahepatic CD4 + T cells which specifically recognized the NS4 protein of HCV were observed. The clonotype of these T lymphocytes was not detectable in the PBMC from these subjects (Minutello et al., 1993). These studies demonstrate that in patients with HCV hepatitis, HCV-specific T lymphocytes can be isolated from the infected liver and the peripheral blood. Their role in the pathogenesis of the liver damage in HCV hepatitis and their relevance for the clearance or persistence of the virus remains to be established. Although neutralization of certain viral infections is possible by humoral immunity only, most microbiological agents can only be cleared from the host with the aid of cellular immunity. Even when the neutralizing capacity of circulating antibodies is established in certain infections, T helper cell activity is generally required to allow B cells to produce the required levels of circulating antibodies, for achievement of neutralization and clearance of the infectious agent. However, certain infectious agents can only be neutralized by means of cellular immunity. In the case of hepatitis C virus, it can be anticipated that T cell immunity may be required for clearance of the virus, since most patients enter into a chronic course of the disease, and since most patients infected with HCV have developed humoral immunity to most of the HCV antigens which can be employed for diagnosis of HCV infection, as described in patent applications no. EP-A-0 318 216, EP-A-0 388 232, EP-A-0 442 394, EP-A-0 484 787, EP-A-0 489 968. However, most of the antibody-positive patients have not been able to clear the virus from the circulation since they remain HCV-PCR positive and, consequently, the detected antibodies have not been protective neither sufficient to neutralize the virus. Possibly, antibodies to other epitopes which are currently not included in HCV diagnostic assays may be capable of neutralizing HCV infection. Such epitopes may be located on the viral membrane proteins E1 and E2, but protection against a wide range of different HCV species may be hampered by the hypervariability of HCV envelope regions. The aim of the present invention is to provide T cell stimulating polypeptides and peptides derived from the HCV structural region. Another aim of the present invention is to provide T cell stimulating polypeptides and peptides as defined above for use in the preparation of an HCV immunogenic composition. Another aim of the present invention is to provide T cell stimulating peptides or polypeptides derived from the E1 region of HCV. Another aim of the present invention is to provide T cell stimulating peptides or polypeptides from HCV as specified above which contain either T helper cell (CD4 + ) epitopes and/or CTL (CD8 + ) epitopes. Another aim of the present invention is to provide recombinant polypeptides containing the same. Another aim of the present invention is to provide therapeutic as well as prophylactic compositions comprising the same. Another aim of the present invention is to provide prophylactic or therapeutic compositions comprising said polypeptides. Another aim of the present invention is to provide methods for preventing or treating HCV infection based on the same. Detailed description of the invention More particularly, the present invention describes a polypeptide of about 8 to about 20 amino acids comprising or consisting of at least 8 contiguous amino acids selected from the E1 region of the HCV polyprotein, with said contiguous amino acids containing a T-cell stimulating epitope, and provided that said polypeptide is different from any known T cell epitope containing HCV peptide or polypeptide described from any of the above-mentioned regions. The latter known HCV polypeptides and peptides are described for screening for B cell epitopes. Such polypeptides and peptides are for instance mentioned in EP-A-0 318 216, EP-A-0 388 232, EP-A-0 442 394, EP-A-0 484 787, EP-A-0 489 968, WO 92/22571, Lesniewski et al., 1993; Weiner et al., 1993; etc The content of these applications is hereby incorporated by reference. Even more particularly, the present invention relates to the use of polypeptides as described above for the preparation of an HCV immunogenic composition. The expression "HCV immunogenic composition" refers to the prevention or treatment of HCV infection. The term "HCV polyprotein" refers to any HCV polyprotein disclosed in the art and is reviewed in. Okamoto et al. 1992, such as the type 1a HCV polyprotein of the HC-J1 isolate, such as the HCV polyprotein of the type 2a HC-J6 isolate (Okamoto et al., 1991), the type 2b HC-J8 isolate (Okamoto et al., 1992). According to this definition, any variation already observed within any of the described regions of HCV is to be considered as part of the definition of HCV polyprotein. For example, numerous types and subtypes are disclosed in Bukh et al., 1993, Bukh et al., 1994, Stuyver et al., 1993a, Stuyver et al., 1993b, Stuyver et al., 1994a, Stuyver et al., 1994c. Moreover, conservative substitutions may be introduced in these HCV polyproteins according to the present invention. The term "conservative substitution" as used herein denotes that one amino acid residue has been replaced by another, biologically similar residue. Examples of conservative substitutions include the substitution of one hydrophobic residue such as isoleucine, valine, leucine or methionine for another, or the substitution of one polar residue for another such as between arginine and lysine, between glutamic and aspartic acids or between glutamine and asparagine and the like. The term "conservative substitution" also includes the use of a substituted amino acid in place of an unsubstituted parent amino acid provided that antibodies raised to such a polypeptide also immunoreact with the corresponding polypeptide having the unsubstituted amino acid. The term "antibody" refers to a molecule that is a member of a family of glycosylated proteins called immunoglobulins, which can specifically combine with an antigen. The word "antigen" has been used historically to designate an entity that is bound by an antibody, and also to designate the entity that induces the production of the antibody. More current usage limits the meaning of antigen to that entity bound by an antibody, while the word "immunogen" is used for the entity that induces antibody production. Where an entity discussed herein is both immunogenic and antigenic, reference to it as either an immunogen or antigen will typically be made according to its intended utility. The term "corresponds" in its various grammatical forms as used in relation to peptide sequences means the peptide described plus or minus up to three amino acid residues at either or both of the amino- and carboxy-termini and containing only conservative substitutions in particular amino acid residues along the polypeptide sequence. "Epitope" refers to that portion of a molecule that is specifically bound by a T cell antigen receptor or an antibody combining site. The term "immunoreact" in its various forms means binding between an antigen as a ligand and a molecule containing an antibody combining site such as a Fab portion of a whole antibody. The expression "T-cell stimulating epitope" or T cell epitope according to the present invention refers to an epitope capable of stimulating T-cells. A T-cell stimulating epitope may be selected according to the present invention by monitoring the lymphoproliferative response (as detailed in the Examples section) towards polypeptides containing in their amino acid sequence at least 8 contiguous amino acids derived from the E1 region of any HCV polyprotein. Said lymphoproliferative response may be measured by either a T-helper assay comprising in vitro stimulation of PMBC from patients with hepatitis C infection with varying concentrations of peptides to be tested for T-cell stimulating activity and counting the amount of radiolabelled thymidine uptake. Said lymphoproliferative response may also be measured by means of a CTL assay measuring the lytic activity of cytotoxic cells using 51 Cr release. Proliferation is considered positive when the stimulation index (mean cpm of antigen-stimulated cultures/mean cpm of controle cultures) is more than 1, preferably more than 2, most preferably more than 3. In order to select a T-cell stimulating epitope containing peptide, the results of these lymphoproliferative assays are compared and immunodominant T-cell epitope containing polypeptides or peptides are selected. The results of the lymphoproliferative assays against certain peptides may also be compared between clinical non-responders and responders to Interferon-α treatment. The lymphoproliferative response towards a series of synthetic, overlapping peptides representing the HCV core, E1 and E2/NS1 sequences and a recombinant NS3 protein was monitored in 32 patients with chronic HCV hepatitis as disclosed in the Examples section of the present invention. Consequently, the present invention represents a selection of immunodominant T cell epitopes from a series of antigens covering the E1 region. From the examples section, it is clear that not only peptide pools 2 and 3 and peptides NS1-5* and NS1-7 * but also, pools 4, 5, 6 and 9 and NS3, reacted frequently with hepatitis C patients (Table 4) while infrequent reactivity could only be observed in normal controls with the same polypeptides (Table 5). It is obvious from the data presented in Table 4 that large areas of the HCV structural region, such as pool 1 (amino acids 5-72) and pools 7 and 8 (amino acids 427-578) show little reactivity with T cells of infected patients, even with patients with a response to IFN-α treatment. Most strikingly, however, it was found that while the dominant B cell response to hepatitis C.in general is located to the core aminoterminus (see also Table 3), the dominant T cell response is directed towards the core carboxyterminal region (see Table 4). In the literature, ample evidence can be found that the core carboxyterminal half contains little or no B cell-reactive epitopes. The words "polypeptide" and "peptide" are used interchangeably throughout the specification and designate a linear series of amino acids connected one to the other by peptide bonds between the alpha-amino and carboxy groups of adjacent amino acids. Polypeptides can be a variety of lengths, either in their natural (uncharged) forms or in forms which are salts, and either free of modifications such as glycosylation, side chain oxidation, or phosphorylation or containing these modifications. It is well understood in the art that amino acid sequences contain acidic and basic groups, and that the particular ionization state exhibited by the peptide is dependent on the pH of the surrounding medium when the protein is in solution, or that of the medium from which it was obtained if the protein is in solid form. Also included in the definition are proteins modified by additional substituents attached to the amino acids side chains, such as glycosyl units, lipids, or inorganic ions such as phosphates, as well as modifications relating to chemical conversions of the chains, such as oxidation of sulfhydryl groups. Thus, "polypeptide" or its equivalent terms is intended to include the appropriate amino acid sequence referenced, subject to those of the foregoing modifications which do not destroy its functionality. The polypeptides of the invention, and particularly the shorter peptides amongst them, can be prepared by classical chemical synthesis. The synthesis can be carried out in homogeneous solution or in solid phase. For instance, the synthesis technique in homogeneous solution which can be used is the one described by Houbenweyl in the book entitled "Methode der organischen chemie" (Method of organic chemistry) edited by E. Wunsh, vol. 15-I et II. THIEME, Stuttgart 1974. The polypeptides of the invention can also be prepared in solid phase according to the methods described by Atherton and Shepard in their book entitled "Solid phase peptide synthesis" (IRL Press, Oxford, 1989). The polypeptides according to this invention can also be prepared by means of recombinant DNA techniques as documented below. The polypeptides or peptides according to the present invention may, as specified above, vary in lenght. The peptides according to the invention contain at least 8 contiguous HCV amino acids. Preferred lengths of peptides are 8, 9, 10, or more (for instance 15 or 20) amino acid residues. The expression "comprised between amino acids X to includes the amino acid X and the amino acid Y. The numbering of the HCV polyprotein used in the present invention refers to the numbering as used for the HCV-J isolate according to Kato et al., 1990. All other HCV isolates known in the art may be aligned to this sequence to obtain the referred HCV polyprotein numbering for each individual HCV isolate. For instance, it is known that type 2 isolates can contain 4 extra codons/amino acids in their E2 sequence, while type 3 sequences have an insertion of 2 amino acids compared to type 1 sequences. The Examples section of the present invention describes T cell epitopes in, amongst other regions of the HCV structural region: the carboxyterminal region of the core protein (aa 73-176), amino acids 192 to 383 of the E1 region, amino acids 397 and 428 and amino acids 571 to 638 of the E2 region, amino acids 1188 to 1463 of the NS3 region. Groups of peptides covering parts of the structural proteins core and E2, and covering the complete E1 protein, as well as a recombinant NS3 protein have been studied. Peptides were tested as group 1 (aa 5-80), group 2 (aa 73-140), group 3 (aa 133-200), group 4 (aa 193-260), group 5 (aa 253-332), group 6 (325-392), group 7 (aa 427-494), group 8 (aa 487-578), and group 9 (aa 571-638) as shown in Table 1. Recombinant NS3 encompassed amino acids 1188 to 1463 of the isolate IG8309, belonging to the 1b subtype group of HCV. The T cell response to the group 3 peptides, as well as to the individual peptides NS1-7 * and NS1-5 * shows a statistically relevant correlation with a decrease in alanine aminotransferase (ALT) and viral RNA levels, which are generally accepted to indicate a more benign course of the disease. A correlation between response to 'a recombinant HCV core protein' and a more benign course of the disease has been described by Botarelli et al. 1993. However, no epitopes have been mapped nor has the sequence and exact position of the recombinant core protein been described in Botarelli et al., 1993. In the present invention, a similar T cell response has been observed to the group 2 peptides (aa 73-140) both in patients responding to IFN-α and in patients non-responding to the same. On the contrary, T cell reactivity to the group 3 peptides (aa 133-200) was observed in responders to interferon-α and differed from the T cell reactivity observed to this region in non-responders to IFN-α treatment. Furthermore, after investigating the reactivity of individual peptides from groups 2 and 3, this specific response correlating with a more benign course of HCV infection, could be further mapped to specific individual peptides termed CORE 23, CORE 25, and CORE 27. Peptide CORE 19, belonging to the group 2 peptides, was also recognized by some of the responders to IFN-α treatment (see Fig. 1). The present invention relates to the use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids253 to 272 in the E1 region of HCV: LPATQLRRHIDLLVGSATLC (SEQ ID NO 21) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-ceil stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 21. The present invention also relates to the use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 265 to 284 in the E1 region of HCV: LVGSATLCSALYVGDLCGSV (SEQ ID NO 22) or any variant to this sequence derived from a nother type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 22. The present invention further relates to the use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 289 to 308 in the E1 region of HCV: QLFTFSPRRHWTTQGCNCSI (SEQ ID NO 23) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 23. The present invention also relates to the use of a polypeptidesof about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptides comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 301 to 320 in the E1 region of HCV: TQGCNCSIYPGHITGHRMAW (SEQ ID NO 24) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 24. The present invention also relates to the use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 313 to 332 in the E1 region of HCV: ITGHRMAWDMMMNWSPTAAL (SEQ ID NO 25) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope, and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 25. The present invention relates more particularly to any of the above-mentioned uses wherein said T cell stimulating epitope is a T cell helper epitope. According to another embodiment, the present invention relates to any of the above-mentioned uses wherein said T cell stimulating epitope is a CTL epitope. The present invention also relates to any of the above-mentioned uses, wherein said polypeptide is incorporated into a prophylactic vaccine composition. According to another embodiment, the present inventionalso relates to any of the above-mentioned uses, wherein said polypeptides is incorporated into a therapeutic vaccine composition. Moreover, the present invention also contemplates a polypeptide consisting of multiple repeats, combinations or mimotopes of any of the contiguous amino acid sequences selected to contain T cell stimulating epitopes as defined above, with said combinations comprising two or more peptides joined into a single structure and with said mimotopes having one or more amino acid variations compared to said peptides as long as said mimotope peptides are capable of providing for immunological stimulation after which the T-cells are reactive with at least one strain of HCV The term "mimotopes" refers to peptides which mimic the polypeptides as defined above immunologically. Since sequence variability has been observed fro HCV, it may be desirable to vary one or more amino acids so as to better mimic the epitopes of different strains. It should be understood that such mimotopes need not be identical to any particular HCV sequence at long as the subject compounds are capable of providing for immunological stimulation after which the T cells are reactive with at least one strain of HCV. The polypeptides as described above, may therefore be subject to insertions, deletions and conservative as well as non-conservative amino acid subtitutions where such changes might provide for certain advantages in their use. The peptides will preferably be as short as possible while still maintaining all of their sensitivity of the larger sequence. In certain cases, it may be desirable to join two or more peptides into a single structure. The formation of such a composite may involve covalent or noncovalent linkages. The present invention also contemplates the uses as defined above, with said polypeptide being a recombinant polypeptide expressed by means of an expression vector comprising a nucleic acid insert encoding a polypeptide as defined above. In order to carry out the expression of the T-cell containing polypeptides of the invention in bacteria such as E. coli or in eukaryotic cells such as in S. cerevisiae, or in cultured vertebrate or invertebrate hosts such as insect cells, Chinese Hamster Ovary (CHO), COS1, BHK, and MDCK cells, the following steps are carried out: transformation of an appropriate cellular host with a recombinant vector, or by means of adenoviruses, influenza viruses, BCG, and any other live carrier systems, in which a nucleotide sequence coding for one of the polypeptides of the invention has been inserted under the control of the appropriate regulatory elements, particularly a promoter recognized by the polymerases of the cellular host or of the live carrier system and in the case of a prokaryotic host, an appropriate ribosome binding site (RBS), enabling the expression in said cellular host of said nucleotide sequence, culture of said transformed cellular host under conditions enabling the expression of said insert. Recombinant virus or live carrier vectors may also be directly used as live vaccines in humans. According to a preferred embodiment, thepresent invention contemplates any of the uses as defined above wherein said polypeptide is operably linked to a pathogen related immunogen such as the HCV envelope proteins E1 and E2, or the HCV NS3, NS4 or NS5 immunogens, or a HCV peptide containing a B cell epitope. The phrase "operatively linked" as used herein means that the linkage does not interfere with the ability of either of the linked groups to function as described; e.g., to function as a T or B cell determinant. Thus, operatively linking not only includes covalent linkages, but also include linkages capable of inducing T cell function. Thephrase "pathogen related" as used herein designates a polypeptide that is capable of inducing the T cell function that immunoreacts with a pathogen in native form. The defined polypeptides can be employed as such or in combination with HCV B cell epitopes, HBsAg or HBcAg particles, HIV immunogens, HTLV immunogens. HCV peptides containing preferred B cell epitopes are detailed in for instance EP-A-0 489 968 and WO 93/18054. method for operatively linking individual polypeptides through an amino acid residue side chain to form an immunogenic conjugate, i.e., a branched-chain polypeptide polymer, are well known in the art. Those methods include linking through one or more types of functional groups on various side chains and result in the respective polypeptide backbones being covalently linked (coupled) but separated by at least one side chain. Useful side chain functional groups include epsilon-amino groups, beta- or gamma-carboxyl groups, thiol (-SH) groups and aromatic rings (e.g. tyrosine and histidine). Methods for linking polypeptides using each of the above functional groups are described in Erlanger (1980), Aurameas et al. (3.978) and U.S. Patent Neo. 4,493,795 to Nestor et al. In addition, a site-directed coupling reaction, as described in Rodwell et al. (1985), can be carried out so that the biological activity of the polypeptides is not substantially diminished. Furthermore, as is well known in the art, the HBcAg protein and polypeptide immunogen can be used in their native form or their functional group content may be modified by succinylation of lysine residues or reaction with cysteine-thiolactone. A sulfhydryl group may also be incorporated into either polypeptide by reaction of amino functions with 2-iminothiolane or the N-hydroxysuccinimide ester of 3-(3-dithiopyridyl) propionate. The polypeptides can also be modified to incorporate spacer arms, such as hexamethylene diamine or other bifunctional molecules of similar size, to facilitate linking. Any polypeptide immunogen against which antibody production is desired can be linked to the polypeptide of the present invention protein to form an immunogenic conjugate of this invention. In preferred embodiments the polypeptide immunogen is a pathogen related immunogen and the conjugate has the capacity to induce the production of antibodies that immunoreact with the pathogen when injected in an effective amount into an animal. Exemplary immunogens of particular importance are derived from bacteria such as B. pertussis, S. typosa, S. Paratyphoid A and B, C. diptheriae, C. tetani, C. botulinum, C. perfringens, B. anthracis, P. pestis, P. multocida, V. cholerae, N. meningitides, N. gonorrhea, H. influenzae, T. palladium, and the like; immunogens derived from viruses such as polio virus, adenovirus, parainfluenza virus, measles, mumps, respiratory syncytical virus, influenza virus, equine encephalomyeitis virus, hog chloera virus, Newcastle virus, fowl pox virus, rabies virus, feline and canine distemper viruses, foot and mouth disease virus, human and simian immunodeficiency viruses, and the like; rickettsiae immunogen such as epidemic and endemic typhus, and the spotted fever groups, and the like. Immunogens are well known to the prior art in numerous references such as U.S. Patent No. 3,149,036, No. 3,983,228, and No. 4, 069, 313; in Essential Immunology, 3rd Ed., by Roit, published by Blackwell Scientific Publications; in Fundamentals of Clinical Immunology, by Alexander and Good, published by W.B. Saunders; and in Immunology, by. Bellanti, published by W.B. Saunders. Particularly preferred pathogen related immunogens are those described in United States Patent No. 4,625,015, No. 4,544,500, No. 4,545,931, Neo. 4,663,436, No. 4,631,191, No. 4,629,783 and in Patent Cooperation Treaty International Publication No. WO87/02775 and No. WO87/02892, all of whose disclosures are incorporated herein by reference. The present invention relates particularly to a peptide consisting of at least 8 contiguous amino acids of the sequence of any of the following peptides, with said peptides containing a T cell epitope: a) LPATQLRRHIDLLVGSATLC (SEQ ID NO 21) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 21; b) LVGSATLCSALYVGDLCGSV (SEQ ID NO 22) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 22; c) QLFTFSPRRHWTTQGCNCSI (SEQ ID NO 23) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 23; d) TQGCNCSIYPGHRITGHRMAW (SEQ ID NO 24) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 24; or e) ITGHRMAWDMMMNWSPTAAL (SEQ ID NO 25) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 25. Moreover, the present invention contemplates an immunogenic composition consisting of or comprising at least one of the peptides or polypeptides as defined above mixed with a pharmaceutical acceptable excipient. Before administration to patients, formulants may be added to the polypeptides or peptides of the invention. A liquid formulation is preferred. For example, these formulants may include oils, polymers, vitamins, carbohydrates, amino acids, salts, buffers, albumin, surfactants, or bulking agents. Preferably carbohydrates include sugar or sugar alcohols such as mono, di, or polysaccharides, or water soluble glucans. The saccharides or glucans can include fructose, dextrose, lactose, glucose, mannose, sorbose, xylose, maltose, sucrose, dextran, pullulan, dextrin, alpha and beta cyclodextrin, soluble starch, hydroxyethyl starch and carboxymethylcellulose, or mixtures thereof. Sucrose is most preferred. "sugar alcohol" is defined as a C4 to C8 hydrocarbon having an -OH group and includes galactitol, inositol, mannitol, xylitol, sorbitol, glycerol, and arabitol. Mannitol is most preferred. These sugars or sugar alcohols mentioned above may be used individually or in combination. There is no fixed limit to amount used as long as the sugar or sugar alcohol is soluble in the aqueous preparation. Preferably, the sugar or sugar alcohol concentration is between 1.0 w/v% and 7.0 w/v%, more preferable between 2.0 and 6.0 w/v%. Preferably amino acids include levorotary (L) forms of carnitine, arginine, and betaine; however, other amino acids may be added. Preferred polymers include polyvinylpyrrolidone (PVP) with an average molecular weight between 2,000 and 3,000, or polyethylene glycol (PEG) with an average molecular weight between 3,000 and 5,000. It is also preferred to use a buffer in the composition to minimize pH changes in the solution before lyophilization or after reconstitution. Most any physiological buffer may be used, but citrate, phosphate, succinate, and glutamate buffers or mixtures thereof are preferred. Most preferred is a citrate bluffer. Preferably, the concentration is from 0.01 to 0.3 molar. Surfactants that can be added to the formulation are shown in EP patent applications No. EP 0 270 799 and EP 0 268 110. Additionally, polypeptides can be chemically modified by covalent conjugation to a polymer to increase their circulating half-life, for example. Preferred polymers, and methods to attach them to peptides, are shown in U.S. Patent Nos. 4,766,106; 4,179,337; 4,495,285; and 4,609,546. Preferred polymers are polyoxyethylated polyols and polyethylene glycol (PEG). PEG is soluble in water at room temperature and has the general formula: R(O-CH 2 -CH 2 ) n O-R where R can be hydrogen, or a protective group such as an alkyl or alkanol group. Preferably, the protective group has between 1 and 8 carbons, more preferably it is methyl. The symbol n is a positive integer, preferably between 1 and 1,000, more preferably between 2 and 500. The PEG has a preferred average molecular weight between 1000 and 40,000, more preferably between 2000 and 20,000, most preferably between 3,000 and 12,000. Preferably, PEG has at least one hydroxy group, more preferably it is a terminal hydroxy group. It is this hydroxy group which is preferably activated. However, it will be understood that the type and amount of the reactive groups may be varied to achieve a covalently conjugated PEG/polypeptide of the present invention. Water soluble polyoxyethylated polyols are also useful in the present invention. They include polyoxyethylated sorbitol, polyoxyethylated glucose, polyoxyethylated glycerol (POG), etc. POG is preferred. One reason is because the glycerol backbone of polyoxyethylated glycerol is the same backbone occurring naturally in, for example, animals and humans in mono-, di-, triglycerides. Therefore, this branching would not necessarily be seen as a foreign agent in the body. The POG has a preferred molecular weight in the same range as PEG. The structure for POG is shown in Knauf et al., 1988, and a discussion of POG/IL-2 conjugates is found in U.S. Patent No. 4,766,106. Another drug delivery system for increasing circulatory half-life is the liposome. Methods of preparing liposome delivery systems are discussed in Gabizon et al., 1982; and Szoka, 1980. Other drug delivery systems are known in the art and are described in, e.g. Poznansky, 1984. After the liquid pharmaceutical composition is prepared, it is preferably lyophilized to prevent degradation and to preserve sterility. Methods for lyophilizing liquid compositions are known to those of ordinary skill in the art. Just prior to use, the composition may be reconstituted with a sterile diluent (Ringer's solution, distilled water, or sterile saline, for example) which may include additional ingredients. Upon reconstitution, the composition is preferably administered to subjects using those methods that are known to those skilled in the art. As stated above, the polypeptides and compositions of this invention are used to treat human patients to prevent or treat any of the above-defined disease states. The preferred route of administration is parenterally. In parenteral administration, the compositions of this invention will be formulated in a unit dosage injectable form such as a solution, suspension or emulsion, in association with a pharmaceutically acceptable parenteral vehicle. Such vehicles are inherently nontoxic and nontherapeutic. Examples of such vehicles are saline, Ringer's solution, dextrose solution, and Hanks' solution. Nonaqueous vehicles such as fixed oils and ethyl oleate may also be used. A preferred vehicle is 5% dextrose in saline. The vehicle may contain minor amounts of additives such as substances that enhance isotonicity and chemical stability, including buffers and preservatives. The dosage and mode of administration will depend on the individual. More particularly, the present invention contemplates a composition as defined above for use in a method of immunizing against HCV, comprising administrating a sufficient amount of at least one of the polypeptides as defined above, possibly accompanied by pharmaceutically acceptable adjuvants, to produce an immune response. More particularly, said immunogenic composition is a vaccine composition. Even more particularly, said vaccine composition is a prophylactic vaccine composition. Alternatively, said vaccine composition may also be a therapeutic vaccine composition. The prophylactic vaccine composition refers to a vaccine composition aimed for preventing HCV infection and to be administered to normal persons who are not yet infected with HCV. The therapeutic vaccine composition refers to a vaccine composition aimed for treatment of HCV infection and to be administered to patients being infected with HCV. The polypeptides described in the present invention can be modified with lipid (lipopeptides, e.g. PAM 3 Cys), and formulated with alum, monophosphoryl lipid A, pluronics, SAF1, Ribi, trehalose-6,6-dimycolate or other immunostimulating compounds known to those skilled in the art, as to enhance their immunogenicity. Also, the present invention contemplates according to a preferred embodiment, a composition as defined above, with said composition comprising in addition to any of the T cell-stimulating polypeptides as defined above, a peptide or polypeptide containing at least one B-cell epitope of HCV, and/or a structural HCV polypetide, and/or a non-structural HCV polypeptide. According to a yet other preferred embodiment, the present invention contemplates a composition as defined above for use in a method of treatment of HCV, comprising administrating a sufficient amount of at least one of the polypeptides as defined above, possibly accompanied by pharmaceutically acceptable adjuvants, to allow treatment of HCV infection. In this case the polypeptides of the present invention can be employed in the form of therapeutic vaccine, aiming at the induction of a sufficient level of T cell function for clearance of Hepatitis C virus infection. According to yet another preferred embodiment, the present invention contemplates a composition as defined above, with said composition comprising sin addition to any of the polypeptides as defined above, a peptide or polypeptide containing at least one B-cell epitope of HCV, and/or a structural HCV polypeptide, and/or a non-structural HCV polypeptide. According to yet another embodiment, the present invention contemplates a composition wherein said polypeptides as defined above are mixed with HBsAg or HBcAg particles, HBV immunogens, HIV immunogens and/or HTLV immunogens. In addition, the present invention contemplates the use of a recombinant expression vector comprising a nucleic acid insert encoding a polypeptide as defined above for the preparation of a HCV immunogenic composition. Figure legends Figure 1 : Evolution of the lymphoproliferative responses and transaminase activities in HCV patient No. 632. AST depicts aspartate aminotransferase, ALT depicts alanine aminotransferase; SI: simulation index; P1 to P6 refers to the groups of peptides 1 to 6 as disclosed in Table 1. Figure 2 : Frequencies of lymphoproliferation responses to peptide pools 1-9, single peptides NS1-7*, NS1-5* and recombinant NS3 protein in healthy controls, interferon (IFN) responders and IFN non-responders. Figure 3 : represents the part of the sequence of the isolate IG8309 which has been tested, with said part extending from with Gly at position 41 to Ser at position 318 (SEQ ID NO 57). Figure 4: represents an alignment of the HCV structural regions. Figure 5. Alignment of E2 region spanning amino acid positions 571 to 638. Figure 6. Aligment of NS3 sequences spanning amino acid positions 1188 to 1465. EXAMPLES Example 1. Patients studied The patients studied consisted of 19 males and 13 females, aged between 27 and 71 (mean age: 49.9 years). The diagnosis of chronic HCV hepatitis was based on a) a documented elevation of alanine aminotransferase of 2 times the upper limit of normal for at least six months; b) the presence of HCV-specific serum antibodies detected by two second generation enzyme immunoassay tests (UBI test and Innotest HCV AbII, Innogenetics, Antwerp Belgium) and c) absence of clinical, histological or serological signs of other viral, toxic, metabolic, hereditary or auto-immune hepatitis. The patients were randomized to receive either the standard treatment consisting of 3 million units Interferon α-2b (INTRON A) given thrice weekly for 24 weeks or an experimental treatment consisting of an induction phase of 6 million units Interferon α-2b thrice weekly for eight weeks, followed by a maintenance phase of titrated doses of interferon of 6 to 1 million units thrice weekly until biochemical and virological remission (alanine aminotransferase activity normal, plasma hepatitis C virus-RNA undetectable) was achieved. Patients were considered clinical responders when a normalization of alanine aminotransferase activity was observed on at least two successive control visits during treatment with al least one month interval. As controls for the specificity of the lymphoproliferative responses, 18 healthy individuals aged 25-58 years (mean 38.6), 10 males and 8 females were selected. These subjects were negative for HCV antibodies and HCV-RNA. One subject had a history of past hepatitis B virus infection and 7 had antibodies to HBsAg as a result of vaccination. A liver biopsy was performed in all patients prior to the initiation of Interferon-α therapy. The histological status was defined according to conventional histological classification (Knodell et al., 1981). Based on the definition of clinical responders given above, 18 subjects could be considered clinical responders to Interferon-α. The most relevant clinical, pathological and virological data of both groups are summarized in Table 2. Although the responder group contained more women and the non-responder group more men than theoretically expected, the observed imbalances were not significant (X 2 -test). The duration of the disease in each subject was estimated based on anamnestic data (surgery with multiple transfusions, intravenous drug abuse, professional exposure through needle stick accident, etc.) or patient file data displaying chronically fluctuating and elevated transaminase levels. The disease duration varied from one to 32 years. The mean disease duration was 9.2 ± 9.2 years in responders and 6.8 ± 5.4 years in non-responders. Although the responder group contained more subjects treated with the experimental protocol and the non-responder group more subjects treated with the standard protocol, the imbalance was not significant X 2 -test). Twenty six out of 32 patients (81%) were infected with HCV of genotype 1b. The genotypes 3a, 4a and 5a were found in 4, 1 and 1 subject, respectively. Anamnestic data allowed us to retrieve the source of infection. Blood transfusions are the possible source of the HCV infection in 14 subjects, IV drug abuse in 3 patients and needle stick accidents in 3 others. No source of infection could be traced back in 12 subjects. Most patients (20 out of 32) showed pathological lesions compatible with chronic active hepatitis in a mild, moderate or severe form. Seven patients displayed signs of chronic persistent hepatitis. In two subjects the biopsy showed only aspecific lesions and in two others signs of liver cirrhosis were observed. Example 2. Analysis of the humoral immune response INNO-LIA HCV AbII (Innogenetics, Belgium) was employed to detect antibodies to peptide epitopes from the core, NS4a+b and NS5a region. From each patient a serum sample obtained before the start of the interferon therapy was examined and sometimes, additional follow-up samples were also tested. All 32 patients studied had circulating antibodies towards HCV demonstrated by two commercially available enzyme immunoassays. Using a peptide-based immunoblot assay (INNO-LIA HCV AbII) we were able to partially define the specificities of these antibodies. Sera from 31 patients were examined at least once with this assay and in 20 subjects the assay was applied on two sera taken with an interval of 4 (Patient 635) to 124 weeks (Patient 606). Table 3 shows the results of this survey. Apart from the reactivity pattern with the antigens employed (4 individually spotted core peptides, a mixture of NS4 peptides defining a fifth line and a selection of NS5 peptides creating a sixth line), Table 3 also shows the HCV genotype and the moment at which the serum was taken with respect to the start of the interferon therapy. The data clearly indicate that the antibody recognition pattern of an individual patient hardly changes over time. The only differences observed in the 20 paired samples were single step alterations in the intensity of the reactions. As well in responders as in non-responders to interferon we observed the same hierarchy in the serological reaction patterns. When indeterminate or weak reactions are not taken into consideration, the following hierarchy appears: Core2 > NS4 > NS5 > Core1 > Core4 > Core3. Example 3. Detection of HCV RNA and HCV genotyping Reverse transcription and PCR was performed as described previously (Stuyver et al, 1993). PCR products were further processed for genotyping by means of the Inno-LiPA genotyping assay (Stuyver et al., 1993). The results of the genotyping assays are included in Table 3. Example 4. Analysis of the cellular immune response 4.1. Synthesis of HCV antigens Nine groups of peptides (pools) corresponding to Core, E1 and E2/NS1 sequences, two single peptides not included in these pools corresponding to E2/NS1, and a recombinant protein representing the central part of NS3-HCV genotype 1b, were used for in vitro stimulation of PBMC. Each group pooled 4-6 different 20-mer peptides which overlapped 8 amino acids. Groups 1, 2 and 3 included mainly core peptides with amino acid positions 5-80, 73-140 and 133-200, respectively (Table 1). Groups 4, 5 and 6 predominantly encompassed E1 peptides with amino acid positions 193-260, 253-332 and 325-392, respectively. Groups 7, 8 and 9 comprised E2/NS1 peptides with amino acid positions 427-494, 487-578 and 571-638, respectively. The two additional single peptides (NS1-7 * , and NS1-5*) covered amino acids from 397 to 428 of the E2 sequence (Table 1). A fusion protein containing the NS3 sequence was expressed in E. coli and covered HCV amino acids 1188 to 1463 of the Belgian isolate IG8309. Peptides were dissolved in the buffers shown in Table 1 and added to the cultures at a final concentration of 10 µg/ml. At this peptide concentration, the concentration of dissolving buffers in the cell cultures was not toxic or inhibitory. Preliminary experiments were performed to ascertain this. NS3 protein was used at a final concentration of 1.5 µg4/ml. Tetanus toxoid (WHO, Copenhagen, Denmark), used as a positive control antigen, was added to the culture media at a final concentration of 10 µg/ml. All the peptides were synthesized on either PepSyn K resin (Millipore) functionalized with the acid labile linker 4-(a-Fmoc-amino-2',4'-dimethoxybenzyl) phenoxyacetic acid, or TentaGel S-RAM resin (Rapp Polymere) functionalized with the same linker which yields peptide amides upon cleavage. t -Butyl-based side chain protection and Fmoc-a-amino protected amino acid derivatives were used. The guanidino group of arginine was 2,2,5,7,8-pentamethylchroman-6-sulfonyl-protected. The imidazole group of histidine was protected with either t -Boc or trityl and the sulfhydryl group of cysteine was protected with a trityl group. Couplings were carried out using preformed O-pentafluorophenyl esters except in the case of arginine where TBTU(O-(1H-benzotriazol-1-yl)-N,N,N',N', tetramethyluronium tetrafluoroborate, Novabiochem) was used as the activating agent in the presence of 2 equivalents of the base N-methylmorpholine and 1 equivalent of 1-hydroxybenzotriazole. Occasionally, glutamine, asparagine, and tryptophan were also coupled using TBTU activation. In these cases, the trityl-protected derivatives of glutamine and asparagine (Millipore), and the t -Boc-protected derivative of tryptophan (Novabiochem) were used. All syntheses were carried out on a Milligen 9050 PepSynthesizer (Millipore) using continuous flow procedures. Following cleavage of the peptides with trifluoroacetic acid in the presence of appropriate scavengers and precipitation with diethylether, all peptides were analyzed by C 18 -reverse phase chromatography. HCV amino acid sequences corresponding to the viral nucleocapsid (core) and E1 proteins were based on the HC-J1 sequence described by Okamoto et al . (1990) Japan. J. Exp. Med. (1990) 60:167-177). HCV sequences starting at amino acid residue Gly 451 were taken from the sequences reported by Choo et al . (1991) Proc. Natl. Acad. Sci. USA (1991) 88:2451-2455. Most peptide sequences were chosen such that the peptides would overlap each other by 8 amino acid residues. 4.2. T cell proliferation assays The medium used for all cell cultures consisted of RPMI 1640 supplemented with 25 mM HEPES, 2 mM L-glutamine, 50 U/ml penicillin and 50 µ g/ml streptomycin (all from Gibco Europe, Gent, Belgium), 5x10 -5 M 2-mercaptoethanol (Sigma, St. Louis, Mo.) and 10% heat-inactivated pooled human AB serum. This AB serum was obtained from healthy blood donors with blood group AB + and was only used when antibodies to HCV and HCV-RNA were absent. This "complemented" RPMI 1640 medium will hereafter be designated "complete medium". PBMC were isolated from heparinized venous blood by isopycnic density centrifugation on Ficoll Hypaque (Lymphoprep, Nyegaard, Denmark) and suspended in complete medium. 4x10 5 PBMC in 200 µl of complete medium were cultured in 96 well roundbottomed microplates (Falcon Plastics) in the absence (unstimulated controls) or presence of varying concentrations of antigens for 5 days at 37°C in an atmosphere of 5% CO 2 in air. 0.5 µCi ( 3 H)-thymidine was then added to each well and 16 to 20 h later the cultures were harvested onto glass fiber filters using a multichannel cell harvester (PHD, Cambridge, MA) to measure the incorporation of ( 3 H)-thymidine by liquid scintillation counting in an LKB-Wallac 8100 counter (LKB, Bromma, Sweden). Results are expressed as stimulation index (SI; mean cpm of antigen-stimulated cultures/mean cpm of control cultures). Proliferation was considered positive when stimulation index was >3. In some figures the results are expressed as cpm (mean cpm of antigen-stimulated cultures - mean cpm of control cultures). Standard deviations of the mean cpm of triplicate cultures were consistently below 10%. The occurrence of in vivo primed HCV-specific memory T lymphocytes was examined using a lymphoproliferation assay. PBMC from 32 patients with chronic HCV were stimulated in vitro with pools of 4 to 6 partially overlapping, synthetic peptides representing the core, E1 and E2/NS1 regions of HCV type 1a, with 2 overlapping, single peptides from the amino-terminus of HCV type 1a and with a recombinant fusion protein containing the NS3 sequence of HCV type 1b. In all but 2 patients (#610 and #636) at least 2 and up to 11 (#633) assays were performed. In patient # 632 for example lymphoproliferation was examined on 8 different occasions between week 4 and 54 following the start (week 0) of the Interferon therapy. Figure 1 shows the results of these assays in correlation with the biochemical (ALT/AST) response to therapy. Four weeks after the start of Intron-A (Schering Plough) a normalization of the transaminase levels was observed. PBMC's from the patient consistently and vigorously proliferate upon stimulation with peptide pools 2 and 3. The responses to the other antigen preparations were less vigorous and less reproducible, suggesting that the number of memory cells recognizing these epitopes is lower. Antigens that did not induce a proliferative response with a stimulation index (SI) 3 at any time are not represented in the graph. To analyze and summarize the results of 135 assays performed in the 32 HCV patients, we have chosen to consider the response of an individual patient to a particular antigen preparation (peptide pools 1 to 9, NS1-5*, NS1-7* or NS3 protein) as significant when it induces SI's 3 in at least half of the assays performed. The results shown in Table 4 have been obtained using this scoring method. The Table shows the antigen recognition pattern of chronic HCV patients towards the 12 antigen preparations standardly used. Apart from the individual patient number and the number of assays performed with PBMC's from each subject, Table 4 also shows the time frame wherein these assays were executed. The start of the Interferon therapy serves as the reference point, week 0. None of the patients responded to all the antigens. PBMC's from 13 of 18 (72%) clinical responders and 12 of 14 (85%) non-responders proliferated in response to at least one antigen preparation. All but one antigen preparation, peptide pool 8, induced a proliferative response in at least one subject. The most frequent responses were to peptide pools 2 and 3. Whereas both interferon-responders and non-responders proliferated equally well to peptide pool 2 (56% and 57%, respectively), non-responders reacted less well to peptide pool 3 (29% or 4 of 14) than responders (44% or 8 of 18). Similar imbalances were observed for the reactions to peptide pools 5 and 9, that were more frequently recognized by non-responders (43% and 43%, respectively) than by responders (17% and 11%, respectively). Clinical non-responders to interferon therapy also reacted more frequently (57% or 8 of 14) upon stimulation with the NS3 protein than responders (24% or 4 of 17). However, none of these differences in proliferative response rates to peptide pools 3, 5 and 9 or to NS3 protein reached statistical significance (p<0.05 in 2 -test). A striking and significant difference (p=0.01 in 2 -test) was observed for the response rate of responders and non-responders to peptides NS1-5* and NS1-7*. Indeed, 8 of 17 responders recognized one or both peptides while none of the non-responders did so. A summary of the results of all these proliferation assays is provided in Figure 2, in which the response rates of the HCV patients as well as 18 healthy control subjects towards the 12 antigen preparations. Indeed, to establish the relevance of the proliferative responses observed in HCV patients, PBMC's from 18 healthy control subjects were stimulated with the same antigen preparations. Overall, 27 assays were performed: a single assay in 10 subjects, two in 7 volunteers and 3 in one individual. In 12 control subjects none of the antigens induced a proliferative response. In 6 subjects one or more antigens induced a proliferative response with an SI 3 in a unique assay or in at least half of the assays performed. Table 5 shows the antigens that induced the proliferation in these subjects. Although Figure 2 suggests that proliferative responses occur more frequently in HCV patients than in healthy controls, these differences do not always reach statistical significance (p< 0.05). Peptide pools 2 and 3 and the NS3 protein clearly (p<0.05) induce more frequent proliferative responses in the whole group of HCV patients than in healthy controls. Most of these differences are also significant when interferon responders and non-responders are each compared to the healthy control group. Only for the proliferative response to NS3 of interferon responders this is no longer valid. Although the frequency of proliferative response to peptide pool 5 in healthy controls and HCV patients were not significantly different, they turned out to be so (p<0.03) when only the non-responders were compared to the control subjects. All other differences did not reach the p<0.05 level. Example 5. Fine specificity of the recognition of the HCV core region by PBMC from clinical responders: T cell epitope localization in the core carboxyterminal region Since peptide pools 2 and 3 elicited proliferative responses in a large fraction of HCV patients, we have examined which peptides from these pools were inducing these responses. The stimulatory capacity of single peptides on PBMC's from healthy control subjects was tested as well. Twenty-three proliferation assays were performed with PBMC's from 17 control subjects. Peptides core C17, core C21 and core C31 were recognized by 2, 1 and 1 subject or 12%, 6% and 6% of subjects, respectively. PBMC's were prepared from 11 HCV patients that responded to interferon therapy. Eight subjects had displayed a proliferative response to either one or both peptide pools 2 and 3, whereas 3 patients had not. Nineteen assays were performed. The scoring system for positive reactions was as described in example 4. Table 6 summarizes the results of these 19 assays and demonstrates the consistency of the assay results. Indeed, PBMC's from the patients that had not reacted to the peptide pools did not proliferate upon stimulation with any of the individual peptides. The PBMC's from the patients that had displayed a proliferative response before, also reacted upon stimulation with one or several peptides from these pools. At least one and up to five of these peptides were recognized by these patients. The most immunogenic region of the HCV core sequence seems to be located between amino acids 109 and 176. Peptides C27 (AA 157-176), recognized by 6 of the 8 proliferative responders, turns out to be the most immunodominant one, followed by C25 which is recognized by 5 patients, and C23 and C19 which are recognized by 3 subjects. Example 6 The fine specificity of the lymphoproliferative responses was tested again with new samples, the majority of which was obtained from other patients than those analyzed in example 5. Five patients (two αIFN responders and three αIFN non-responders) and 16 normal controls were examined. Table 7 shows the results of the assays performed in chronic hepatitis C patients. The highest LPR observed in both αIFN responders tested was towards aa positions : 73-92 (C13); 109-128 (C19); 121-140 (C21); 145-164 (C25); 157-176 (C27). Only aa residues 121-140 (C21) and 133-152 (C23) elicited a high PLR in two α IFN non-responders. Therefore, the use of peptides C13, C19, C25 and/or C27 in prophylactic or therapeutic vaccine compositions may be particularly advantageous. REFERENCES Maertens, G., Ducatteeuw, A., Stuyver, L., Vandeponseele, P., Venneman, A., Wyseur, A., Bosman, F., Heijtink, R. & de Martynoff, G. 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Claims: Use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 253 to 272 in the E1 region of HCV: LPATQLRRHIDLLVGSATLC (SEQ ID NO 21) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 21. Use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 265 to 284 in the E1 region of HCV: LVGSATLCSALYVGDLCGSV (SEQ ID NO 22) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 22. Use of a polypeptide of about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 289 to 308 in the E1 region of HCV: QLFTFSPRRHWTTQGCNCSI (SEQ ID NO 23) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 23. Use of a polypeptideof about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 301 to 320 in the E1 region of HCV: TQGCNCSIYPGHITGHRMAW (SEQ ID NO 24) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 24. Use of a polypeptideof about 8 to about 20 amino acids for the preparation of an HCV immunogenic composition, with said polypeptide comprising or consisting of at least 8 to about 20 contiguous amino acids selected from the region comprised between amino acids 313 to 332 in the E1 region of HCV: ITGHRMAWDMMMNWSPTAAL (SEQ ID NO 25) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and with said contiguous amino acids containing a T-cell stimulating epitope, and wherein said polypeptide mimics the T-cell immunological stimulation properties of the polypeptide as represented in SEQ ID NO 25. Use of a polypeptide according to any of claims 1 to 5, wherein said T cell stimulating epitope is a T cell helper epitope. Use of a polypeptide according to any of claims 1 to 5 wherein said T cell stimulating epitope is a CTL epitope. Use of a polypeptide according to any of claims 1 to 7, wherein said polypeptide is incorporated into a prophylactic vaccine composition. Use of a polypeptide according to any of claims 1 to 7, wherein said polypeptide is incorporated into a therapeutic vaccine composition. A polypeptide consisting of multiple repeats, combinations or mimotopes of any of the contiguous amino acid sequences selected to contain T cell stimulating epitopes as defined in any of claims 1 to 9, with said combinations comprising two or more peptides joined into a single structure and with said mimotopes having one or more amino acid variations compared to said peptides as long as said mimotope peptides are capable of providing for immunological stimulation after which the T-cells are reactive with at least one strain of HCV. Use of a polypeptide according to any of claims 1 to 9, with said polypeptide being a recombinant polypeptide expressed by means of an expression vector comprising a nucleic acid insert encoding a polypeptide according to any of claims 1 to 9. Use of a polypeptide according to any of claims 1 to 9 which is operably linked to a pathogen related immunogen, such as the HCV envelope proteins E1 and E2, or the HCV NS3, NS4 or NS5 immunogens, or a HCV peptide containing a B cell stimulating epitope. A peptide consisting of at least 8 contiguous amino acids of the sequence of any of the following peptides, with said peptides containing a T cell epitope: a) LPATQLRRHIDLLVGSATLC (SEQ ID NO 21) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 21; b) LVGSATLCSALYVGDLCGSV (SEQ ID NO 22) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 22; c) QLFTFSPRRHWTTQGCNCSI (SEQ ID NO 23) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 23; d) TQGCNCSIYPGHITGHRMAW (SEQ ID NO 24) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 24; or e) ITGHRMAWDMMMNWSPTAAL (SEQ ID NO 25) or any variant to this sequence derived from another type of HCV as depicted in Figure 4, and wherein said peptide mimics the T-cell immunological stimulation properties of the peptide as represented in SEQ ID NO 25. An immunogenic composition consisting of or comprising at least one of the peptides or polypeptides according to claim 13 mixed with a pharmaceutically acceptable excipient. A vaccine composition according to claim 14. A prophylactic vaccine composition according to claim 15. A therapeutic vaccine composition according to claim 15. A composition according to any of claims 14 to 17, with said composition comprising in addition to any of the polypeptides according to claim 13, a peptide or polypeptide containing at least one B cell stimulating epitope of HCV, and/or a structural HCV polypeptide, and/or a non-structural HCV polypeptide. A composition according to any of claims 14 to 17, wherein said polypeptide according to claim 13 is mixed with HBsAg or HBcAg particles, HBV immunogens, HIV immunogens and/or HTLV immunogens. Use of a recombinant expression vector comprising a nucleic acid insert encoding a polypeptide as defined in any of claims 1 to 9 for the preparation of a HCV immunogenic composition.

Inventors: DELEYS ROBERT, LEROUX-ROELS GEERT, MAERTENS GEERT, DELEYS, ROBERT, LEROUX-ROELS, GEERT, MAERTENS, GEERT
Applicants: INNOGENETICS NV, INNOGENETICS N.V.
Application year: 1994
Main classification: C12N15
IPC codes: A61K39, C07K14